As a paper sheet receiving and feeding device configured to receive and feed paper sheets such as banknotes, there has been known, for example, a paper sheet receiving and feeding device including a winding drum that winds up paper sheets together with a tape (hereinafter referred to as “paper sheet receiving and feeding device of a winding type”).
Conventionally, as a paper sheet receiving and feeding device of a winding type and a banknote processing device including the same, devices disclosed in JP8-67382A, JP2000-123219A and JP2005-293389A have been known, for example.
In the conventional banknote receiving and feeding device of a winding type, a pair of tapes or one tape and a winding drum are adapted to sandwich banknotes therebetween. When the winding drum winds up the tape(s), the banknotes are received and stored one by one. On the other hand, in the banknote receiving and feeding device, when the winding drum winds off the tape(s), the banknotes are fed one by one. In the banknote receiving and feeding device disclosed in JP2005-293389A, the drive of the drum is controlled such that a transport speed by the tape and a transport speed of a transport path are equal to each other, and that spacings between the banknotes to be stored are the same with each other.
Recently, the paper sheet processing device of a winding type has been required to have a smaller size but to have a larger capacity. As one of effective measures to cope with these requirements, it is considered to reduce a diameter of the winding drum of the banknote receiving and feeding device of a winding type.
However, when an outer peripheral length of the winding drum is smaller than a distance between a front edge of a wound-up banknote and a front edge of a banknote to be subsequently wound up (hereinafter referred to as “storing pitch”), an outer peripheral length of the tape is increased every time when the tape is wound up. Thus, the outer peripheral length of the tape and the storing pitch become substantially equal to each other, and this condition continues for a while. Under this condition, when a large number of banknotes are wound up in succession, the banknotes to be stored are unevenly wound, i.e., the banknotes are wound up on substantially the same position on the winding drum. Thus, the winding drum is divided into a section having a larger tape diameter and a section having a smaller tape diameter, when seen from the center of the winding drum. Since the thicknesses of the banknote and the tape are small, a considerably large number of banknotes have to be wound up until this condition is eliminated, which is achieved by an increase in the outer peripheral length of the tape. For example, when banknotes that are transported in a constant cycle are wound up in succession, there is a possibility that one hundred or more banknotes might be unevenly wound up on substantially the same position on the winding drum. In this case, since the center of gravity of the drum is displaced, it may be difficult to control the winding speed of the tape, and/or the tape may be caught by a guide disposed along the outer periphery of the drum when the drum winds off the tape. Herein, “substantially the same position on the winding drum” means substantially the same direction when seen from the center of the winding drum.
The above problem of unevenly winding up the banknotes to be stored on substantially the same position on the winding drum is described with reference to FIG. 11.
As shown in FIG. 11(a), in the conventional banknote processing device, a banknote having been transported along a transport path (banknote to be subsequently wound up) is wound up, together with a tape, by a winding drum. Herebelow, an outer diameter of the winding drum is represented as d1, an outer peripheral length thereof is represented as l1, an outer diameter of an outermost periphery of the tape wound up by the winding drum (hereinafter referred to as “outer diameter of the tape”) is represented as d2, and an outer peripheral length thereof (hereinafter referred to as “outer peripheral length of the tape”) is represented as l2. For example, the outer diameter d2 of the tape is 49.3 mm. In addition, a storing pitch y between the banknotes to be wound up by the winding drum at a predetermined rotational speed is, e.g., 155 mm. In addition, a distance between a rear edge of the banknote wound up by the winding drum and a front edge of the banknote to be subsequently wound up, which reaches a contact point between the transport path and the tape wound up by the winding drum, (hereinafter referred to as “storing spacing”) is e.g., 79 mm. At this time, the outer peripheral length l2 of the tape is a product of the outer diameter d2 of the tape and a constant π, i.e., a value thereof is about 155 mm. Namely, a difference between the outer peripheral length l2 of the tape and the storing pitch y becomes extremely small. In this case, the front edge of the wound-up banknote and the front edge of the banknote to be subsequently wound up are located on substantially the same position on the winding drum.
As a result, as shown in FIG. 11(b), the banknotes are unevenly wound up, i.e., the wound-up banknotes are located on substantially the same position on the winding drum. This condition is eliminated, as the tape continues to be wound up together with the banknotes so that the outer peripheral length l2 of the tape increases. However, since the tape and the banknotes are thin, when the tape is wound up only for a while, the increase in the outer peripheral length l2 of the tape is small. That is, the problem continues for a long period of time.
Further, even when the outer diameter d1 of the winding drum is smaller than 49.3 mm, as the tape is wound up together with the banknotes, the outer peripheral length l2 of the tape approaches the storing pitch y. Also in this case, as shown in FIG. 11(b), the banknotes are unevenly wound up, i.e., the wound-up banknotes are located on substantially the same position on the winding drum.
On the other hand, when the storing pitch y between almost all the stored banknotes is sufficiently small relative to the outer peripheral length l2 of the tape, the above problem does not occur. (In general, when the outer peripheral length l2 of the tape approaches integral multiples of the storing pitch y, the above problem occurs. However, a case in which the outer peripheral length l2 of the tape approaches k (k is an integer not less than 2) times the storing pitch y (i.e., l2 substantially equals to k multiplied by y) can be handled similarly to a case in which the outer peripheral length l2 of the tape approaches one time the storing pitch y (i.e., l2 substantially equals to y). Hereafter, the case in which l2 substantially equals to y is described.) For example, in the banknote receiving and feeding device disclosed in JP2000-123219A, the transport speed and the tape winding speed are substantially the same with each other, the storing pitch is substantially the same as the transport pitch, and the outer diameter d1 of the winding drum is so large that the storing pitch y is sufficiently small relative to the outer peripheral length l1 of the winding drum from the first. Owing to these design requirements, the above problem does not occur. On the other hand, in this banknote receiving and feeding device, if the diameter of the winding drum is reduced so that the outer peripheral length of the winding drum becomes smaller than the transport pitch, there is a possibility that the above problem might occur, because of the deviation from the above design requirements for preventing the problem.
In addition, in the banknote receiving and feeding device disclosed in JP8-67382A, the outer peripheral length of the tape is not considered. Further, in this banknote receiving and feeding device, the tape winding speed is larger than the transport speed. Thus, the storing pitch becomes larger than the transport pitch. Even when the outer peripheral length of the tape is larger than the transport pitch, the above problem may occur if the storing pitch is larger than the outer peripheral length of the tape.
In addition, in the banknote processing device disclosed in JP2005-293389A, the relationship between the outer diameter of the tape, when it is unevenly wound up, and the storing pitch is not considered. Thus, the above problem may occur in this banknote processing device.